Resettable, heat actuatable fire link

ABSTRACT

A resettable fire link is described comprising a releasable member, gripping means for engaging said releasable member in the normal position and for releasing said releasable member in the activated position. Said gripping means comprises heat responsive means for causing said gripping means to move to the normal position in response to an ambient temperature and for causing said gripping means to move to the activated position in response to a preselected increase in said ambient temperature. Mechanical activation means are also provided for movement from a first withdrawn to a second extended position. In said first withdrawn position, the mechanical activation means allows said gripping means to move freely between its normal and said activated position, as aforesaid. The mechanical activation means also may independently cause said gripping means to move to the activated position. As a result, a novel heat and/or remote mechanically activated fire link is provided which is ideally suited for disposition in a &#34;dirty&#34; environment such as might be found in a poorly filtered ventilating system. 
     The fire link of the present invention maintains excellent heat response characteristics, is resettable, and will function under fail-safe conditions, that is, either in response to a preselected increase in ambient temperature, or in response to the remote activation of the mechanical activation means. If a malfunction occurs in one of the alternate activation means, the other activation means is free to function.

BACKGROUND OF THE INVENTION

The present invention is generally an improvement relating to the heatactuated releasing device as described in my prior U.S. Pat. Nos.3,725,972, entitled "Fire Link and Method of Actuating Same;" and3,889,314, entitled "Heat Actuated Link."

In each of the aforementioned patents, resettable heat actuatedreleasing devices are described. One of these devices, for example,incorporates remotely controlled heating means for electrically heatingthe bimetallic element to actuate the device. In certain installationselectrical heating of links may not be preferred either due to the useof a pneumatic or hydraulic system in other portions of the installationand/or due to the existence of an operating environment whereinelectrical heating is not economical. In each of the links described inthe aforementioned patents, the sole source of movement for releasingthe releasable member is the heat induced distortion of the bimetallicelement with respect to the base or mounting element. Obviously, in thelack of heat (whether produced by a rise in the ambient temperature orby auxiliary heating means) neither of the aforementioned fire linkswill open spontaneously.

SUMMARY OF THE PRESENT INVENTION

The present invention relates to an improved releasing device which isresponsive either to a preselected increase in the ambient temperaturearound that link or to remote activation through mechanical activationmeans. In particular, a link is provided having a releasable member andgripping means for engaging the releasable member in the normal positionand for releasing the releasable member in the activated position. Thisgripping means comprises heat responsive means for causing the grippingmeans to move to the normal position in response to a preselectedambient temperature and to move to the activated position in response toa preselected increase in that ambient temperature. In the preferredembodiment, this heat responsive means is a bimetallic element which mayhave either a substantially straight or serpentine configuration asdescribed in each of the aforementioned patents, U.S. Pat. Nos.3,725,972 and 3,889,314, which patents are hereby incorporated as iffully set forth herein.

Mechanical activation means for remotely releasing the releasable memberis also provided which does not interfere with the function of theaforementioned heat responsive means. When in a first withdrawnposition, the mechanical activation means allows the gripping means tomove freely between the normal and the activated positions as aforesaid.Upon remote activation, this means independently causes the grippingmeans to release the releasable member regardless of the temperature ofthe bimetallic element. The mechanical activation means of the preferredembodiment comprises a force producing means and a ram. The ram need bepowered only towards the bimetallic element, that is, to cause aseparation of the bimetallic element from the mounting element. Upondeactivation, the normal function of the bimetallic element will causethe return of the ram to the withdrawn position. In the event that thebimetallic element is unable to return the ram to the withdrawnposition, the link cannot be reset, thereby acting as a safety featurewhich requires that further attention be given either to the forceproducing means and/or to the bimetallic element prior to its furtheruse.

In order to maintain excellent heat response characteristics, the forceproducing means is disposed on the opposite side of the mounting elementfrom the bimetallic element and is spaced away from the mounting elementby a bracket means which creates an air channel therebetween. Only asmall portion of the ram extends from the force producing means throughthe aforementioned air channel and through a void defined in themounting element. The surface of the bimetallic element which faces themounting element is engaged by said ram at a single point. The result isa minimum interference between the heat responsive means and themechanical activation means.

Accordingly, a primary object of the present invention is the provisionof a heat actuatable releasing device which is also capable of remotemechanical activation. A further object of the present invention is theprovision of a releasing device having a heat responsive means andmechanical activation means which are so interrelated that neither'sfunction is interfered with by the failure of the other. Another objectof the present invention is the provision of a remotely activatablereleasing device ideally suited for use in a "dirty" environment. Theseand other objects of the present invention will become apparent from thefollowing more detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a preferred embodiment of the present invention,characterized by a serpentine bimetallic element; and

FIG. 2 is an enlarged cross-section of the embodiment shown in FIG. 1taken as indicated by the line and arrows 2--2 in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

Although specific forms of the invention have been selected forillustration in the drawings, and the following description is drawn inspecific terms for the purpose of describing these forms of theinvention, this description is not intended to limit the scope of theinvention which is defined in the appended claims.

FIG. 1 is a top view of the preferred embodiment link of the presentinvention, designated generally 12. The link 12 generally comprises areleasable member or pawl 18, a mounting element designated generally10, a bimetallic element designated generally 14, and a mechanicalactivation means designated generally 15. The mounting element,designated generally 10, and the bimetallic element, designatedgenerally 14, together comprise a gripping means for normally engagingthe releasable member 18 and for releasing the releasable member inresponse to an increase in ambient temperature. The link is designed foruse in automatically actuated equipment forming a part of fire fightingsystems. The embodiment shown in FIG. 1 is intended to respond to anincrease in ambient temperature by allowing the separation of thereleasable member 18 from the remainder of the link 12.

As shown in FIG. 1, various attachment means are provided to ensureflexibility in installation. The mounting element 10 of the link of thepresent invention has two attachment sites 22 and 23 for cables, chainsor straps. Further means for attachment are normally positioned at thefar end of the releasable member, which attachment means are not shownin the drawings.

Referring now to FIG. 2, the interrelationship between the mountingelement 10, the bimetallic element 14, and the pawl 18 is demonstrated,together with the interrelationship between each of the aforementionedelements and the mechanical activation means, designated generally 15.The mounting element 10 is substantially planar and is attached to thebimetallic element 14 by fastening means 16 which are rivets, or othermetal fasteners. The end of the mounting element 10 which engages thepawl 18 is differentiated into an offset portion 26 and a strikerportion 57.

The bimetallic element is shown attached by means of the aforementionedfastening means 16 to the mounting element 10 near the end of themounting element which is remote from its interconnection with the pawlor releasable member 18. In its normal position, the bimetallic elementis disposed so that pin 20 will extend through a void defined in theoffset portion 26 of the mounting element 10, and then through a hole inthe releasable portion 18, terminating in an end which is close to ortouching the striker portion 57. The end of the pin 20 which is remotefrom the bimetallic element is beveled to allow the releasable member tobe manually inserted. When the link is in its normal (unheated)position, engagement of the releasable member 18 is effected by pushingthe releasable member 18 against the bevel of the pin 20 thereby forcingthe pin 20 away from the striker portion 57 and allowing the pawl 18 toslide into position in which the hole in the pawl aligns with the pinand is pierced thereby as pin 20 returns to its normal position.

The bimetallic element designated generally 14 should be so formed thatit assumes the normal position shown in the solid lines in FIG. 2 whenexposed to the ambient temperature of its expected installation. Thebimetallic element itself is made of a conventional bimetallic materialselected for its characteristic strength, elastic memory and ability toresist fatigue which bent to the desired configuration. The bimetallicelement is made of two flat strips of dissimilar material adheredtogether in any well known manner. Bimetallic elements are commonly usedin thermostats and the like. See for example the bimetallic fire linksdisclosed in U.S. Pat. Nos. 3,725,972 and 3,889,314.

The operation of the gripping means in selectively gripping or releasingthe releasable member 18 in response to a preselected increase in theambient temperature around the device is quite simple. As seen in FIG.2, the configuration of the bimetallic element 14 exposes a largesurface area to the ambient air which surrounds the link, which surfacearea is substantially uninterferred with by the mechanical activationmeans 15. As the temperature of the air around the link rises, thebimetallic element is heated, causing the element to assume theconfiguration shown in phantom.

Although the serpentine configuration of the bimetallic element 14 isillustrated in the drawings, in an alternate embodiment the bimetallicelement may be configured as illustrated in my prior issued U.S. Pat.No. 3,725,972.

The mechanical activation means of the present invention comprises aforce producing means 102 which may be a pneumatic or hydraulic cylinder(in an electrical embodiment, a solenoid) and a ram 100. The ram 100 maybe a piston rod or other similar rod which is acted upon by the forceproducing means 102 to selectively separate the mounting elementdesignated generally 10 from the bimetallic element designated generally14, thereby releasing the releasable member 18 as shown in phantom. Thetip of ram 100 is rounded to minimize contact and wear between the ram100 and the undersurface of the tip portion of bimetallic element 14. Inthe event that the link of the present invention was activated by heatonly (the force producing means was not independently activated to moveram 100 into the position shown in phantom in FIG. 2), the ram wouldremain as shown in the solid position. Alternatively, if either heat andthe force producing means activated the link or alternatively, if theforce producing means were the sole source of activation of the link, aposition of the ram as shown in phantom in FIG. 2 would be assumed andretained as long as pressurization through tube 103 or other activationmeans continued to apply a force to the ram. Although a double actingcylinder may be utilized as the force producing means 102, the presentinvention contemplates that upon deactivation of the force producingmeans 102, the elastic memory of the bimetallic element 14 will causethe ram 100 to move from the phantom to the solid lined position in FIG.2. By not substituting a double acting cylinder for the force producingmeans 102, a natural check on the function of the bimetallic element andthe mechanical activation means occurs in that any damage which mightoccur during a fire or due to wear and so forth, will become immediatelyapparent if the ram 100 and the bimetallic element 14 do not return tothe solid lined position in FIG. 2.

Since it is of great importance to maintain the heat activationcharacteristics of the link, an air channel is formed between the forceproducing means designated generally 102 and the heat responsive elementof the link. If, for example, the force producing means 102 weredirectly mounted onto the mounting plate or mounting element designatedgenerally 10 of the link, free flow of ambient air around the link wouldbe interfered with and the substantially higher heat capacity of thehydraulic cylinder or solenoid might draw heat from the bimetallicelement, thereby possibly inhibiting or delaying a heat activatedrelease of the releasable member. The force producing means designatedgenerally 102 is therefore disposed on the opposite side of the mountingelement designated generally 10 from the bimetallic element 14.Furthermore, a U-shaped bracket 105 is utilized to space the forceproducing means apart from the mounting element, which space is spannedby the ram 100 extending therefrom. U-shaped bracket 105 may beconveniently attached to the mounting element 10 at its base 107 byrivet 16. Insulation 109 is provided between the bimetallic element 14and the mounting element to further prevent heat transfer therebetween.Only the tip 110 of ram 100 extends into the space created between thebimetallic element 14 and the mounting element 10, access to which spaceis provided by voids 113 and 115 defined in mounting element 10 and baseportion 107, respectively. Side portion 121 is seen to extendsubstantially parallel to the axis of the ram designated generally 100to supporting portion 123 which is parallel to base portion 107. In theembodiment shown in FIG. 2 wherein the force producing means designatedgenerally 102 is illustrated as a hydraulic cylinder having conduitmeans 103, cylinder portion 125, threaded portion 127, nut 129 and theaforementioned ram designated generally 100, assembly of the unit isrelatively simple in that the cylinder is usually inserted through abore 131 formed in supporting portion 123 after which nut 129 is applieddown over threaded portion 127 to tightly engage the cylinder portion125 against supporting portion 123.

It will be understood that various changes in the details, materials andarrangement of parts which have been herein described and illustrated inorder to explain the nature of this invention may be made by thoseskilled in the art within the principle and scope of the invention asexpressed in the following claims.

It will be further understood that the "Abstract of the Disclosure" setforth above is intended to provide a nonlegal technical statement of thecontents of the disclosure in compliance with the Rules of Practice ofthe U.S. Patent and Trademark Office, and is not intended to limit thescope of the invention described and claimed herein.

I claim:
 1. A resettable fire link comprising,a. a releasable member; b.gripping means associated with said releasable member for engaging saidreleasable member in a normal position, and for releasing saidreleasable member in an actuated position, said gripping meanscomprising at least one mounting element and heat responsive means forcausing said gripping means to move to the normal position in responseto a preselected ambient temperature and for causing said gripping meansto move to the actuated position in response to a preselected increasein said ambient temperature; and c. mechanical activation meansconnected to said mounting element for movement from a first withdrawnto a second extended position, said mechanical activation means in saidfirst withdrawn position allowing said gripping means to move betweensaid normal and said activated position and for causing said grippingmeans to move to the activated position in response to movement of saidmechanical activation means to said second extended position.
 2. Theinvention of claim 1 wherein said heat responsive means moves saidmechanical activation means from the extended to the withdrawn positionin response to said ambient temperature and the deactivation of saidmechanical activation means.
 3. The invention of claim 1 wherein saidgripping means further comprises a mounting element and a bimetallicelement, and wherein said mechanical activation means is mounted on saidmounting element to selectively separate said mounting element from saidbimetallic element.
 4. The invention of claim 3 wherein said mechanicalactivation means further comprises force producing means and a ram, saidforce producing means being disposed on the opposite side of saidmounting plate from said bimetallic element, and least a portion of saidram being disposed through a void defined in said mounting element forengagement with said gripping means.
 5. The invention of claim 4 whereinsaid force producing means comprises a pneumatic cylinder.
 6. Theinvention of claim 5 wherein said force producing means comprises abracket for disposing said cylinder apart from said mounting element,whereby an air passage is created therebetween.
 7. A releasing devicecomprising:a. a first element; b. a heat actuated bimetallic secondelement coacting with said first element to separate from said firstelement in response to temperature change; and c. pneumatic meansconnected to said first element for selectively separating said firstand second elements without interfering with said separation of saidelements in response to temperature change.